The present invention relates to centrifuge vacuum pumps and is directed more particularly to a purging apparatus for removing contaminating liquids such as water from the lubricating oil of vacuum pumps.
Because large quantities of heat can be generated by the friction between a spinning rotor and the air in the rotor space of a high speed centrifuge, it is frequently necessary to maintain a near vacuum within the rotor space. This vacuum may be produced by any of a number of different kinds of vacuum pumps. Many of these pumps have pump housings within which a predetermined depth of lubricating oil must be present in order to assure the maintenance of a good seal between the parts of the pump. In most pumps of this type, the air that is removed by the pump is discharged through an outlet that connects the interior of the pump housing to the open air through a porous filter.
In addition to including vacuum systems, many centrifuges include refrigeration systems to maintain the rotor space at below ambient temperatures. As a result, as the centrifuge is opened and closed during sample insertion and removal, moisture tends to condense on the walls of the rotor space. Later, when the vacuum pump evacuates the rotor space, this condensed moisture will vaporize and the removed by the pump. Over time, this removed moisture tends to accumulate in the lubricating oil of the pump. In large enough quantities, this moisture can not only change the lubricating properties of the oil, but can also result in the formation of emulsions and in a reduction in the base pressure produced by the pump.